Methods for administering a drug by attaching a drug-containing adhesive skin patch to the skin and penetrating the drug from this adhesive skin patch into the skin have commonly been performed so far. On the other hand, administration methods using electrical energy such as iontophoresis (Journal of Pharmaceutical Sciences, Vol. 76, p. 341, 1987) and electroporation (National Publication of International Patent Application No. 1991-502416; and Proc. Natl. Acad. Sci. USA, Vol. 90, pp. 10504-10508, 1993) have been developed as methods for promoting the drug absorption of the skin or mucous membrane. Both iontophoresis and electroporation have been expected to be used as methods for promoting transdermal or transmucosal drug absorption.
Alternatively, Patent Document 1 has proposed a device for increasing transdermal flux of a transdermal pharmaceutical agent by mechanically piercing the skin before the release thereof, in relation to the promotion of drug absorption. This device comprises a sheet having a plurality of openings, a plurality of microblades being integral therewith and extending downward therefrom, and means for anchoring the device to a body surface. In the disclosure, it is intended to provide a device produced at high yields and low costs in a reproducible fashion, which is suitable for minimizing inflammation of the skin and improving the attachment thereof to the skin. A similar device thereto has also been proposed in Patent Document 2.    [Patent Document 1]: National Publication of International Patent Application No. 2000-512529    [Patent Document 2]: National Publication of International Patent Application No. 2001-506904
Furthermore, Patent Document 3 has proposed a device comprising a drug administration tool equipped with a large number of needles for drug administration intended to administer a drug through the skin or mucous membrane by an iontophoretic driving. This device has a needle support and a large number of needles for drug administration provided on the side of the needle support contacting the skin or mucous membrane and is constructed so that the tips of the needles for drug administration located in the vicinity of the center of the needle support protrude further than the tips of the needles for drug administration located in the periphery of the needle support. In the disclosure, it is intended to provide a device that can unerringly insert the fine needles of the drug administration tool into a medicated site when administering a drug by an iontophoretic driving, reduce stimulation to the skin by reasonably dispersing an electric current, and easily control a dose.    [Patent Document 3]: Japanese Patent Laid-Open No. 2003-93521
However, the microblades for piercing skin in the devices disclosed in Patent Documents 1 and 2 are formed by bending the sheet having openings at the positions of the openings. This device might fail to perform reliable piercing treatment because the microblades are flat and therefore deflect by the skin. The microblades present a challenge in that they require exceedingly fine and highly sophisticated machining (punching). Moreover, in the device disclosed in Patent Document 3, the whole platelike member in the main body of the needle support has a lattice pattern, wherein drug-guiding paths are formed, and the needle for drug administration is provided at the position of each lattice point. In this device, when the drug-guiding paths are narrowed, a drug that has passed through the drug-guiding paths is difficult to evenly supply to the needles for drug administration arranged around the drug-guiding paths, depending on the degree of uneven roughness of the surface of the platelike member. Moreover, the amount of the drug supplied from each of the needles for drug administration through skin might vary from one needle for drug administration to another.
Thus, an object of the present invention is to provide an interface for a transdermal drug administration device that can supply a drug almost evenly and favorably from a plurality of projections through skin.